Editing London congestion charge (section)

=== Traffic changes ===

====Traffic volume====
[[File:London congestion cars 2008.png|thumb|Changes in the counts of cars and taxis in London at October 2008 compared to October 2001. Red dots show reductions and blue dots increases. The boundary of the congestion charge is shown in yellow.]]
[[File:London congestion cycles.png|thumb|Changes in the counts of bicycles at October 2008 compared to October 2001. Red dots show reductions and blue dots increases.]]

A year before the congestion zone, TfL set up automatic traffic counters and augmented them with regular classified traffic counts at key locations, to monitor flows.<ref name=tfljune2007/>

TfL's report in June 2007 found that the number of chargeable vehicles entering the zone had reduced by 30% (primarily cars and minicabs, although vans and lorries had decreased by 13%), while there were overall increases in the numbers of taxis, buses, and especially bicycles. The daily profile of traffic flows had changed, with less traffic after 9:30&nbsp;am and a peak immediately before and after the end of the charging period. The level of traffic entering the zone during the morning peak had not reduced as much as at other times.<ref name="tfljune2007" /> The overall level of traffic of all vehicle types entering the central Congestion Charge Zone was consistently 16% lower in 2006 than the pre-charge levels in 2002.<ref name="tfljune2007" /> Year on year, counts of inbound traffic approaching the zone had also seen a distinct and significant 5–7% decline in the number of chargeable vehicles, which was unexplained.<ref name="tfljune2007" /> They had noted a small but pervasive long-term trend of less traffic entering the zone, expected to be a result of people changing their location and lifestyle, perhaps influenced by the charge. The conservative [[Bow Group]] noted that the main effect occurred after 11&nbsp;am.<ref name="bow"/><!-- The Bow Group report commented on Fig 2.2 from the TFL report (page22). Would be nice to have that graph here. -->

Once within the charging zone car and delivery traffic remained unchanged, suggesting that the journeys made by residents and businesses within the zone were broadly unaffected. Changes to the road network over the years has made direct comparisons difficult, but TfL suspect that certain routes used heavily by taxis and buses within the zone have seen substantially increased traffic. On some of the boundary roads traffic numbers had increased slightly but congestion and delays were largely unchanged from 2002 levels.

Following the introduction of the Western Extension, TfL stated that traffic had fallen around 10 to 15% in the extended zone.<ref name="bbc20070521" /> The original zone showed a 4% increase in congestion, following expansion of the congestion charging area and the introduction of discounts extended to residents of the new zone and buffer zone.<ref name="bbc20070711">{{cite news |url=http://news.bbc.co.uk/1/hi/england/london/6292930.stm |date=11 July 2007 |title=Road toll 'cut traffic by 70,000' |work=BBC News |access-date=24 November 2007 |archive-url=https://web.archive.org/web/20150429041145/http://news.bbc.co.uk/2/hi/uk_news/england/london/6292930.stm |archive-date=29 April 2015 |url-status=live}}</ref> TfL assessed the increase in charges in 2005 to have had only a slight impact overall.<ref name="tfljune2007" />

In February 2013, ten years after the scheme introduction, TfL reported a 10% reduction in traffic levels from baseline conditions.<ref name=Guardian012014/> TfL assessed that the scheme has had a significant impact in shifting people away from using cars, contributing to an overall reduction of 11% in vehicle kilometres in London between 2000 and 2012.<ref name=2014assessment/>

A 2024 study found that the congestion charge reduced traffic in downtown London, as well as on untolled suburban roads leading downtown.<ref name=":1">{{Cite journal |last=Herzog |first=Ian |date=2024 |title=The city-wide effects of tolling downtown drivers: Evidence from London's congestion charge |url=https://www.sciencedirect.com/science/article/abs/pii/S0094119024000846 |journal=Journal of Urban Economics |volume=144 |pages=103714 |doi=10.1016/j.jue.2024.103714 |issn=0094-1190}}</ref> The study found that the charge had a progressive impact, as low-skill commuters in the suburbs benefitted from less traffic.<ref name=":1" />

====Traffic speeds====
The charge operates for under one third of the hours in a year and covers around two-thirds of the central London traffic.<ref name="tfljune2007" /> In total 8% of traffic kilometres (miles) are affected by the scheme.<ref name="tfljune2007" /> TfL have extrapolated the trends in road speed in the congestion zone; they have suggested that speeds would have dropped from 17&nbsp;km/h (10&nbsp;mph) in 2003 to 11.5&nbsp;km/h (7&nbsp;mph) by 2006, had the scheme not been put in place.<ref name="tfljune2007" />

A report by TfL in early 2007 indicated that there were 2.27 traffic delays per kilometre (3.65 per mile) in the original charging zone. This compared with a figure of 2.3 per kilometre (3.7 per mile) before the introduction of the congestion charge. After the scheme was introduced they had measured an improvement in journey times of 0.7 minutes per km (1.1 per mile), or 30%. This improvement had decreased to 22% in 2006, and during 2006 congestion levels had increased so that the improvement, compared to the year before the scheme, was just 7%. TfL explained this as a result of changes to road priorities within the zone, delays caused by new pedestrian and road user safety schemes, and, most particularly, a doubling of road works in the latter half of 2006.<ref>{{cite news |url=http://news.bbc.co.uk/1/hi/england/london/7109727.stm |title=Congestion charge 'not working' |date=23 February 2007 |work=BBC News   |access-date=23 November 2007 |archive-url=https://web.archive.org/web/20150429041334/http://news.bbc.co.uk/2/hi/uk_news/england/london/7109727.stm |archive-date=29 April 2015 |url-status=live}}</ref> Utilities were encouraged to complete planned road works in the year preceding the congestion charge, so it would appear that the first year of measurement used for later comparisons would also have been affected by streetworks to some extent.<ref name="bbc20070711" /><ref>{{Cite news |url=https://www.telegraph.co.uk/news/uknews/1454446/London-congestion-charge-not-working.html |archive-url=https://ghostarchive.org/archive/20220112/https://www.telegraph.co.uk/news/uknews/1454446/London-congestion-charge-not-working.html |archive-date=12 January 2022 |url-access=subscription |url-status=live |title=London congestion charge 'not working' |first=Paul |last=Marston |work=The Daily Telegraph |date=16 February 2004 |access-date=24 November 2007}}{{cbignore}}</ref>

TfL reported in January 2014, that despite a reduction of traffic volume within London, traffic speeds have also been getting progressively slower over the past decade, particularly in central London. TfL explains that the historic decline in traffic speeds is most likely due to interventions that have reduced the effective capacity of the road network to improve the urban environment, increase road safety and prioritise public transport, pedestrian and cycle traffic, as well as an increase in road works by utilities and general development activity since 2006. This explains the lower levels of congestion reduction compared to the pre-charge baseline: 8% in 2006, compared to 30% in 2004. Since 2006 this trend towards slower traffic movement has ceased and traffic speeds have remained more stable, as evidenced by GPS satellite tracking data from 2006 to 2012. Indicators of excess delay or congestion also suggest a stable overall picture, with some improvements in the past two years. TfL concludes that while levels of congestion in central London are close to pre-charging levels, the effectiveness of the congestion charge in reducing traffic volumes means that conditions would be worse without the Congestion Charging scheme.<ref name=2014assessment/>